Low cost I‐V system employing variable power supply unit as an electronic load

Abstract

Purpose

The purpose of this paper is to design and construct a low‐cost current‐voltage tester, bearing in mind the short falls of the existing testers and the ever‐increasing price of the testers currently on the market. The I‐V tracer presented in this paper uses a variable external power supply unit (PSU) as the load, in order to obtain the entire operating range of a PV module from open circuit through maximum power to short circuit condition.

Design/methodology/approach

The I‐V tracer presented in this paper was divided into three main sections, mainly the data acquisition system (DAS), which comprises an A/D computer card, temperature card, electromechanical relays, current and voltage transducers, aluminum housed resistors and power MOSFETS, the variable load (programmable variable PSU) and finally the signal processing unit. These components were integrated and finally interfaced to a PC.

Findings

The results obtained using this system compared with the capacitive tester show a low percentage difference of <1 from the comparative I‐V curves measured. The results measured by the PSU tester are also of high accuracy. The findings also demonstrated the fact that most of the components found in most university laboratories can be used to build the PSU tester and still obtain highly accurate results.

Research limitations/implications

Since some components are semiconductors, which have a limited lifetime, they need to be changed if they fail. Mostly the MOSFETS should be replaced when no switching signal is sent.

Practical implications

This low‐cost PSU tester is suitable for researchers in disadvantaged institutions whose research capabilities are limited due to the high cost of this equipment.

Originality/value

The PSU tester uses a variable power supply as the load to measure PV module I‐V curves. The system is capable of measuring up to eight modules at the same time, making it possible to analyze PV modules within the same time frame.

Citation

Simon, M. and Meyer, E.L. (2012), "Low cost I‐V system employing variable power supply unit as an electronic load", Journal of Engineering, Design and Technology, Vol. 10 No. 3, pp. 330-344. https://doi.org/10.1108/17260531211274701